Neste trabalho é enfocado o problema das densidades urbanas econômicas. É feita uma análise de alguns estudos existentes sobre a questão da densidade urbana ideal, sob o ponto de vista econômico, e avaliada, através de um modelo especialmente desenvolvido, qual a influência do custo do transporte coletivo na definição da densidade ideal. Também são discutidos, ainda que de forma não aprofundada, os limites de densidade populacional suportados pelo homem. As conclusões a que se chega são que as densidades econômicas, sob vários critérios, estão, seguramente, acima de 200 habitantes por hectare e que, os limites humanos situam-se em torno de 500 habitantes por hectare. Esses valores, quando comparados às densidades em torno de 40 habitantes por hectare apresentados pelas cidades médias brasileiras, comprovam a forma irracional com que o solo urbano vem sendo ocupado no país, constituindo, o fato, um dos graves problemas que hoje o Brasil enfrenta. / The issue of economical urban densities is analyzed in this study. Related studies about ideal urban densities under the economic point of view are initially discussed, leading to the development of a model designed to evaluate the influence of urban public transportation on the definition of economical densities. Some considerations about density population limits that human beings can bear are also presented. The results suggest that economical densities are over 200 persons/ha whereas the human limits are around 500 persons/ha. The comparison of these values with the density values of Brazilian medium-sized cities (around 40 persons/ha) shows that the urban land occupation in Brazil is not rational, which is currently a serious problems for the country.

Dans ce travail, nous proposons des procédures de test paramétriques et nonparamétrique localement et asymptotiquement optimales au sens de Hajek et Le Cam, pour trois modèles d'asymétrie. La construction de modèles d'asymétrie est un sujet de recherche qui a connu un grand développement ces dernières années, et l'obtention des tests optimaux (pour trois modèles différents) est une étape essentielle en vue de leur mise en application. Notre approche est fondée sur la théorie de Le Cam d'une part, pour obtenir les propriétés de normalité asymptotique, bases de la construction des tests paramétriques optimaux, et la théorie de Hajek d'autre part, qui, via un principe d'invariance permet d'obtenir les procédures non-paramétriques. Nous considérons dans ce travail deux classes de distributions univariées asymétriques, l'une fondée sur un développement d'Edgeworth (décrit dans le Chapitre 1), et l'autre construite en utilisant un paramètre d'échelle différent pour les valeurs positives et négatives (le modèle de Fechner, décrit dans le Chapitre 2). Le modèle d'asymétrie elliptique étudié dans le dernier chapitre est une généralisation multivariée du modèle du Chapitre 2. Pour chacun de ces modèles, nous proposons de tester l'hypothèse de symétrie par rapport à un centre fixé, puis par rapport à un centre non spécifié. Après avoir décrit le modèle pour lequel nous construisons les procédures optimales, nous obtenons la propriété de normalité locale asymptotique. A partir de ce résultat, nous sommes capable de construire les tests paramétriques localement et asymptotiquement optimaux. Ces tests ne sont toutefois valides que si la densité sous-jacente f est correctement spécifiée. Ils ont donc le mérite de déterminer les bornes d'efficacité paramétrique, mais sont difficilement applicables. Nous adaptons donc ces tests afin de pouvoir tester les hypothèses de symétrie par rapport à un centre fixé ou non, lorsque la densité sous-jacente est considérée comme un paramètre de nuisance. Les tests que nous obtenons restent localement et asymptotiquement optimaux sous f, mais restent valides sous une large classe de densités. A partir des propriétés d'invariance du sous-modèle identifié par l'hypothèse nulle, nous obtenons les tests de rangs signés localement et asymptotiquement optimaux sous f, et valide sous une vaste classe de densité. Nous présentons en particulier, les tests fondés sur les scores normaux (ou tests de van der Waerden), qui sont optimaux sous des hypothèses Gaussiennes, tout en étant valides si cette hypothèse n'est pas vérifiée. Afin de comparer les performances des tests paramétriques et non paramétriques présentés, nous calculons les efficacités asymptotiques relatives des tests non paramétriques par rapport aux tests pseudo-Gaussiens, sous une vaste classe de densités non-Gaussiennes, et nous proposons quelques simulations.

7 pp. / Preventing catastrophic stand replacing events are best accomplished through thinning. Lower tree densities result in greater tree growth. Stands with lower tree densities have greater plant diversity. Determining stand conditions will provide a baseline for formulating a plan to improve stand conditions. Thinning around individual trees can improve individual tree health reducing the likelihood of damage from bark beetles, fire or drought.

Systems whose time evolutions are entirely deterministic can nevertheless be studied probabilistically, <em>i. e. </em> in terms of the evolution of probability distributions rather than individual trajectories. This approach is central to the dynamics of ensembles (statistical mechanics) and systems with uncertainty in the initial conditions. It is also the basis of ergodic theory--the study of probabilistic invariants of dynamical systems--which provides one framework for understanding chaotic systems whose time evolutions are erratic and for practical purposes unpredictable. Delay differential equations (DDEs) are a particular class of deterministic systems, distinguished by an explicit dependence of the dynamics on past states. DDEs arise in diverse applications including mathematics, biology and economics. A probabilistic approach to DDEs is lacking. The main problems we consider in developing such an approach are (1) to characterize the evolution of probability distributions for DDEs, <em>i. e. </em> develop an analog of the Perron-Frobenius operator; (2) to characterize invariant probability distributions for DDEs; and (3) to develop a framework for the application of ergodic theory to delay equations, with a view to a probabilistic understanding of DDEs whose time evolutions are chaotic. We develop a variety of approaches to each of these problems, employing both analytical and numerical methods. In transient chaos, a system evolves erratically during a transient period that is followed by asymptotically regular behavior. Transient chaos in delay equations has not been reported or investigated before. We find numerical evidence of transient chaos (fractal basins of attraction and long chaotic transients) in some DDEs, including the Mackey-Glass equation. Transient chaos in DDEs can be analyzed numerically using a modification of the "stagger-and-step" algorithm applied to a discretized version of the DDE.

O feijoeiro-comum (Phaseolus vulgaris L.) é cultivado em vários países ao redor do mundo. O Brasil figura nesse cenário como o segundo maior produtor mundial de grãos secos da cultura, que é a principal fonte de proteína de origem vegetal para o consumo interno. Os nematoides-das-galhas, Meloidogyne incognita e M. javanica, são as principais espécies causadoras da redução de produtividade da cultura. Entretanto, o status hospedeiro das cultivares comerciais atuais ao nematoide das galhas é desconhecido. Da mesma maneira, a distribuição, a resistência de cultivares e os danos de Pratylenchus brachyurus à cultura não foram investigados até o momento. Tendo em vista tal situação, o presente trabalho teve como objetivo determinar quais espécies de nematoides ocorrem em áreas produtoras de feijoeirocomum; verificar a influência de P. brachyurus sobre o crescimento da cultivar Pérola; e o status hospedeiro de cultivares comerciais à P. brachyurus, M. incognita e M. javanica para o possível uso no manejo de áreas infestadas e como fonte de resistência em programas de melhoramento. No levantamento, coletaram-se 69 amostras compostas provenientes de dez cidades nos estados do Paraná e de São Paulo. Os efeitos de diferentes níveis populacionais de P. brachyurus sobre o crescimento de feijoeiro-comum cv. Pérola e sobre parâmetros de resistência [FR=população final (Pf)/população inicial (Pi) e nematoides/g de raiz (Nem./g)] foram avaliados. Trinta e cinco cultivares comerciais de feijoeiro-comum, adaptadas às regiões Centro-Oeste, Sudeste e Sul do Brasil foram avaliadas quanto à sua resistência às três principais espécies encontradas no levantamento, por meio do FR. Classificaram-se as cultivares com FR=1 como suscetíveis. As seguintes espécies foram encontradas nos levantamentos: P. brachyurus, P. crenatus, M. incognita, M. javanica, Rotylenchulus reniformis e Helicotylenchus dihystera. Observou-se redução na massa fresca de raízes (g) da cultivar Pérola, nos tratamentos inoculados com 6,66 e 20 nem./cm³ de solo. Os FR foram maiores nos tratamentos com baixa Pi (0,83 e 2,5 nem./cm³ de solo). Apesar das cultivares terem mostrado FR variado, nenhuma das cultivares apresentou resistência às três espécies estudadas. / Common bean is grown in several countries around the world. Brazil is the second main producing of dry grains, which is the main source of protein for national consumption. The root-knot nematodes, Meloidogyne incognita and M. javanica, are the major species causing yield reduction in that crop. However, the host status of actual cultivars to those rootknot nematodes is unknown. Likewise, the distribution, resistance and damage caused by Pratylenchus brachyurus to the crop were not investigated yet. In view of such situation, the present work aimed survey and identify phytonematodes in common bean fields; verify the effect of P. brachyurus on the growth of the cultivar Pérola; and the host status of actual cultivars to P. brachyurus, M. incognita and M. javanica, in order to enable the management in infested areas, as well as to use like source of resistance in breeding programs. A total of 69 samples from ten cities in Paraná and São Paulo State were surveyed. The effects of different population densities of P. brachyurus on the growth of cultivar Pérola and on parameters of resistance [FR=final population (Pf)/initial population (Pi) and nematodes/g of roots (Nem./g)] were evaluated. Thirty five common bean cultivars, adapted to center-west, southeast and south of Brazil were evaluated for resistance to the three main species found in the survey. The cultivars with FR=1 as susceptible. The following species were found in the surveys: P. brachyurus, P. crenatus, M. incognita, M. javanica, Rotylenchulus reniformis e Helicotylenchus dihystera. Reduction in root fresh weight (g) of cultivar Pérola, in the treatments inoculated with 6.66 and 20 nem./cm³ of soil were observed. The FR was higher in the treatments with low Pi (0.83 and 2.5 nem./cm³ of soil). Despite the cultivars have shown varied FR, resistance for the three nematode species studied was not found in any cultivar.

Ng, Siu Fai = 溫暖稠密物質及高能量密度物理的研究 / 吳肇輝. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaves 126-133). / Abstracts also in Chinese. / Ng, Siu Fai = Wen nuan chou mi wu zhi ji gao neng liang mi du wu li de yan jiu / Wu Zhaohui. / Chapter 1 --- Introduction --- p.16 / Chapter 1.1 --- General review of high energy density physics --- p.16 / Chapter 1.2 --- General review of warm dense matter --- p.20 / Chapter 1.2.1 --- Physics of warm dense matter --- p.20 / Chapter 1.2.2 --- Uncertainties of warm dense matter --- p.23 / Chapter 1.2.3 --- Challenges of warm dense matter studies --- p.25 / Chapter 1.3 --- Use of intense heavy ion beam --- p.27 / Chapter 1.4 --- Motivation and structure of this thesis --- p.32 / Chapter 2 --- Hydrodynamic simulations --- p.34 / Chapter 2.1 --- Lagrangian hydrodynamic code --- p.34 / Chapter 2.2 --- Hydrodynamic equations --- p.35 / Chapter 2.3 --- Artificial viscosity --- p.36 / Chapter 3 --- Equations of state --- p.38 / Chapter 3.1 --- Van der Waals' equation of state --- p.39 / Chapter 3.2 --- Quotidian equation of state --- p.41 / Chapter 3.3 --- Saha-based equation of state --- p.41 / Chapter 3.4 --- Inverse power potentials equation of state --- p.48 / Chapter 3.5 --- Gruneisen-type equation of state --- p.53 / Chapter 3.6 --- Discussion --- p.59 / Chapter 4 --- Single bubble sonoluminescence --- p.63 / Chapter 4.1 --- Introduction --- p.63 / Chapter 4.2 --- Theory of sonoluminescence --- p.65 / Chapter 4.2.1 --- Bubble wall dynamics --- p.66 / Chapter 4.2.2 --- Radiation transport --- p.67 / Chapter 4.2.3 --- Diffusive stability --- p.68 / Chapter 4.3 --- Numerical simulation --- p.68 / Chapter 4.3.1 --- Determination of the ambient radius --- p.69 / Chapter 4.3.2 --- Simulations using SEOS --- p.70 / Chapter 4.3.3 --- Simulations using QEOS --- p.77 / Chapter 4.4 --- Conclusion --- p.82 / Chapter 5 --- Collapsing bubble in ion-beam-heated metal --- p.83 / Chapter 5.1 --- Introduction --- p.83 / Chapter 5.2 --- Bubble collapse --- p.86 / Chapter 5.2.1 --- First step of collapse --- p.88 / Chapter 5.2.2 --- Stagnation point and bubble size --- p.89 / Chapter 5.2.3 --- Outer boundary and metal thickness --- p.91 / Chapter 5.2.4 --- Metal layer just outside bubble --- p.93 / Chapter 5.3 --- Effect of equation of state used --- p.95 / Chapter 5.3.1 --- Inverse power potentials equation of state --- p.95 / Chapter 5.3.2 --- Effect of ionization --- p.97 / Chapter 5.3.3 --- Effect of hard core --- p.97 / Chapter 5.3.4 --- Effect of EOS for metal --- p.97 / Chapter 5.4 --- Effect of proposed experimental parameters --- p.102 / Chapter 5.4.1 --- Initial gas density --- p.102 / Chapter 5.4.2 --- Energy deposition rate --- p.102 / Chapter 5.5 --- Conclusion and discussion --- p.105 / Chapter 6 --- High coupling efficiency compression by intense ion beams --- p.108 / Chapter 6.1 --- Introduction --- p.108 / Chapter 6.2 --- Ion stopping formulation --- p.111 / Chapter 6.3 --- Numerical simulation --- p.112 / Chapter 6.3.1 --- Lithium hydride target --- p.112 / Chapter 6.3.2 --- Underdense aluminum foam --- p.118 / Chapter 6.4 --- Conclusion --- p.119 / Chapter 7 --- Conclusion --- p.121 / Chapter 7.1 --- Summary --- p.121 / Chapter 7.2 --- Suggestions for future work --- p.123 / Bibliography --- p.126

The project was initiated in June of 1958 and financed by the National Science Foundation and the Wildlife Management Department of Utah State University. The broad aspects of the study were to determine if a relationship exists between certain physical and biological factors and benthic fish densities. The project vas divided into two parts: (l) to determine the time and extent of thermal stratification, zooplankton densities, conductivity changes within the lake and conductivity differences between the lake and its tributaries; (2) to determine it a relationship exist between benthic fish densities, temperatures, depths, conductivities and benthic zooplankton densities. The data were analyzed statistically and a separate regression analysis was run on each factor to determine the degree of relationship between that factor and benthic fish densities.

Neurons have the ability to dynamically adjust their own membrane channel densities to modulate the strength of communication with other neurons. This process is integral to such neuronal functions as spatial recognition and memory but has been difficult to measure experimentally. Historically, neuroscientists have used changes in voltage to infer changes in neuronal channel densities. However, voltage is difficult to measure away from the soma. Many important functions in the neuron, like synaptic integration, take place in the dendritic tree where traditional voltage measurements can not be taken. To interrogate the neuron in the dendrites, experimentalists have come to rely on calcium fluorescence based microscopy to infer qualitative information about voltage changes in the dendrites. In these experiments, intracellular calcium changes due to voltage depolarizations are recorded at spatially distributed sites on the dendrites through the binding of calcium to a fluorescent buffer. The recovery of channel densities can be posed as a parameter identification problem in a coupled nonlinear partial differential equation that relates the responses of calcium, the fluorescent buffer and voltage to neuronal stimulation. We convert temporally and spatially distributed fluorescence data into quantitative measurements of voltage sensitive channel densities by inverting slow time-scaled calcium data into fast time-scaled voltage data. Our approach is to solve four interrelated inverse problems corresponding to three different proposed experiments to go from calcium fluorescence to channel densities. In the first experiment, we use subthreshold calcium dynamics to infer the reaction kinetics between calcium arid fluorescent buffer. From these kinetics, we can use suprathreshold voltage stimulation to infer calcium channel densities and recover distributed voltage data. Finally we use the voltage data to infer potassium channel densities in the dendrites. Our algorithm has been shown to recover channel densities for several different calcium channel models and the delayed rectifying potassium channel from simulated noisy fluorescence data in morphologically realistic neurons.

Systems whose time evolutions are entirely deterministic can nevertheless be studied probabilistically, <em>i. e. </em> in terms of the evolution of probability distributions rather than individual trajectories. This approach is central to the dynamics of ensembles (statistical mechanics) and systems with uncertainty in the initial conditions. It is also the basis of ergodic theory--the study of probabilistic invariants of dynamical systems--which provides one framework for understanding chaotic systems whose time evolutions are erratic and for practical purposes unpredictable. Delay differential equations (DDEs) are a particular class of deterministic systems, distinguished by an explicit dependence of the dynamics on past states. DDEs arise in diverse applications including mathematics, biology and economics. A probabilistic approach to DDEs is lacking. The main problems we consider in developing such an approach are (1) to characterize the evolution of probability distributions for DDEs, <em>i. e. </em> develop an analog of the Perron-Frobenius operator; (2) to characterize invariant probability distributions for DDEs; and (3) to develop a framework for the application of ergodic theory to delay equations, with a view to a probabilistic understanding of DDEs whose time evolutions are chaotic. We develop a variety of approaches to each of these problems, employing both analytical and numerical methods. In transient chaos, a system evolves erratically during a transient period that is followed by asymptotically regular behavior. Transient chaos in delay equations has not been reported or investigated before. We find numerical evidence of transient chaos (fractal basins of attraction and long chaotic transients) in some DDEs, including the Mackey-Glass equation. Transient chaos in DDEs can be analyzed numerically using a modification of the "stagger-and-step" algorithm applied to a discretized version of the DDE.

A new automatic algorithm for sampling from monotone, unbounded densities is presented. The user has to provide a program to evaluate the density and its derivative and the location of the pole. Then the setup of the new algorithm constructs different hat functions for the pole region and for the tail region, respectively. For the pole region a new method is developed that uses a transformed density rejection hat function of the inverse density. As the order of the pole is calculated in the setup, conditions that guarantee the correctness of the constructed hat functions are provided. Numerical experiments indicate that the new algorithm works correctly and moderately fast for many different unbounded densities. The proposed algorithm is the first black-box method that works for unbounded densities suggested in the literature. (author's abstract) / Series: Research Report Series / Department of Statistics and Mathematics